Horizontal gene transfer (HGT) or lateral gene transfer (LGT) involves the transmission of genetic material between distinct evolutionary lineages and can be an important source of biological ...innovation. For instance, the acquisition of foreign genes can allow recipient organisms to adapt to new lifestyles or to exploit a novel ecological niche, such as a host environment. HGT has long been recognised as an important factor contributing to the evolution of prokaryotic lineages especially in connection to the evolution of pathogencity 1,2. However, it is becoming increasingly apparent that HGT has also played a role in the evolution of pathogenic traits in eukaryotes 3,4. Here, we consider how HGT has contributed to genome evolution in the oomycetes.
Gene transfer has been identified as a prevalent and pervasive phenomenon and an important source of genomic innovation in bacteria. The role of gene transfer in microbial eukaryotes seems to be of a ...reduced magnitude but in some cases can drive important evolutionary innovations, such as new functions that underpin the colonization of different niches. The aim of this review is to summarize published cases that support the hypothesis that horizontal gene transfer (HGT) has played a role in the evolution of phytopathogenic traits in fungi and oomycetes. Our survey of the literature identifies 46 proposed cases of transfer of genes that have a putative or experimentally demonstrable phytopathogenic function. When considering the life-cycle steps through which a pathogen must progress, the majority of the HGTs identified are associated with invading, degrading, and manipulating the host. Taken together, these data suggest HGT has played a role in shaping how fungi and oomycetes colonize plant hosts.
Biological communities are normally composed of a few abundant and many rare species. This pattern is particularly prominent in microbial communities, in which most constituent taxa are usually ...extremely rare. Although abundant and rare subcommunities may present intrinsic characteristics that could be crucial for understanding community dynamics and ecosystem functioning, microbiologists normally do not differentiate between them. Here, we investigate abundant and rare subcommunities of marine microbial eukaryotes, a crucial group of organisms that remains among the least-explored biodiversity components of the biosphere. We surveyed surface waters of six separate coastal locations in Europe, independently considering the picoplankton, nanoplankton, and microplankton/mesoplankton organismal size fractions.
Deep Illumina sequencing of the 18S rRNA indicated that the abundant regional community was mostly structured by organismal size fraction, whereas the rare regional community was mainly structured by geographic origin. However, some abundant and rare taxa presented similar biogeography, pointing to spatiotemporal structure in the rare microeukaryote biosphere. Abundant and rare subcommunities presented regular proportions across samples, indicating similar species-abundance distributions despite taxonomic compositional variation. Several taxa were abundant in one location and rare in other locations, suggesting large oscillations in abundance. The substantial amount of metabolically active lineages found in the rare biosphere suggests that this subcommunity constitutes a diversity reservoir that can respond rapidly to environmental change.
We propose that marine planktonic microeukaryote assemblages incorporate dynamic and metabolically active abundant and rare subcommunities, with contrasting structuring patterns but fairly regular proportions, across space and time.
•Regular proportions of abundant and rare microeukaryotes across space and time•Contrasting structuring patterns in abundant and rare regional communities•Considerable phylogenetic diversity in the rare microeukaryote biosphere•Metabolically active taxa are present among rare planktonic microeukaryotes
Logares et al. report regular proportions of abundant and rare marine microbial eukaryotes across space and time and contrast structuring patterns in abundant and rare regional communities. Logares et al. find considerable phylogenetic diversity and metabolically active taxa in the rare planktonic microeukaryotic biosphere.
One of the deepest branches in the tree of life separates the Archaea from the Bacteria. These prokaryotic groups have distinct cellular systems including fundamentally different phospholipid ...membrane bilayers. This dichotomy has been termed the lipid divide and possibly bestows different biophysical and biochemical characteristics on each cell type. Classic experiments suggest that bacterial membranes (formed from lipids extracted from Escherichia coli, for example) show permeability to key metabolites comparable to archaeal membranes (formed from lipids extracted from Halobacterium salinarum), yet systematic analyses based on direct measurements of membrane permeability are absent. Here, we develop a new approach for assessing the membrane permeability of approximately 10 μm unilamellar vesicles, consisting of an aqueous medium enclosed by a single lipid bilayer. Comparing the permeability of 18 metabolites demonstrates that diether glycerol-1-phosphate lipids with methyl branches, often the most abundant membrane lipids of sampled archaea, are permeable to a wide range of compounds useful for core metabolic networks, including amino acids, sugars, and nucleobases. Permeability is significantly lower in diester glycerol-3-phosphate lipids without methyl branches, the common building block of bacterial membranes. To identify the membrane characteristics that determine permeability, we use this experimental platform to test a variety of lipid forms bearing a diversity of intermediate characteristics. We found that increased membrane permeability is dependent on both the methyl branches on the lipid tails and the ether bond between the tails and the head group, both of which are present on the archaeal phospholipids. These permeability differences must have had profound effects on the cell physiology and proteome evolution of early prokaryotic forms. To explore this further, we compare the abundance and distribution of transmembrane transporter-encoding protein families present on genomes sampled from across the prokaryotic tree of life. These data demonstrate that archaea tend to have a reduced repertoire of transporter gene families, consistent with increased membrane permeation. These results demonstrate that the lipid divide demarcates a clear difference in permeability function with implications for understanding some of the earliest transitions in cell origins and evolution.
Amphibian Perkinsea Smilansky, Vanessa; Richards, Thomas A
Current biology,
01/2023, Letnik:
33, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Vanessa Smilansky and Thomas A. Richards introduce Perkinsea - a lineage of freshwater parasitic protists that infect certain amphibians and cause of severe Perkinsea infection.
How do distinct species cofunction in symbiosis, despite conflicting interests? A new collection of articles explores emerging themes as researchers exploit modern research tools and new models to ...unravel how symbiotic interactions function and evolve.
The genesis of the eukaryotes was a pivotal event in evolution and was accompanied by the acquisition of numerous new cellular features including compartmentalization by cytoplasmic organelles, ...mitosis and meiosis, and ciliary motility. Essential for the development of these features was the tubulin cytoskeleton and associated motors. It is therefore possible to map ancient cell evolution by reconstructing the evolutionary history of motor proteins. Here, we have used the kinesin motor repertoire of 45 extant eukaryotes to infer the ancestral state of this superfamily in the last common eukaryotic ancestor (LCEA).
We bioinformatically identified 1624 putative kinesin proteins, determined their protein domain architectures and calculated a comprehensive Bayesian phylogeny for the kinesin superfamily with statistical support. These data enabled us to define 51 anciently-derived kinesin paralogs (including three new kinesin families) and 105 domain architectures. We then mapped these characters across eukaryotes, accounting for secondary loss within established eukaryotic groupings, and alternative tree topologies.
We show that a minimum of 11 kinesin families and 3 protein domain architectures were present in the LCEA. This demonstrates that the microtubule-based cytoskeleton of the LCEA was surprisingly highly developed in terms of kinesin motor types, but that domain architectures have been extensively modified during the diversification of the eukaryotes. Our analysis provides molecular evidence for the existence of several key cellular functions in the LCEA, and shows that a large proportion of motor family diversity and cellular complexity had already arisen in this ancient cell.
Digest Richards, Thomas J.
Evolution,
February 2019, Letnik:
73, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Species differences are maintained by the cumulative effect of factors that reduce gene flow between divergent lineages. In this issue, Karrenberg et al. quantify multiple genetic and environmental ...barriers to gene exchange between two closely related plant species and find that adaptation to divergent environments has the greatest effect on reproductive isolation.
Digest Richards, Thomas J.
Evolution,
February 2019, Letnik:
73, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Which genome contributes most to patterns of adaptive trait divergence in Drosophila melanogaster across environmental clines? In this issue, Lasne et al. find that genetic variation associated with ...adaptive traits is mostly distributed between autosomal and mitochondrial genomes with a negligible contribution from the X chromosome.
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